Full blood count Haemoglobin

A raised haemoglobin occurs in polycythaemia (primary and secondary to chronic hypoxaemia) and in haemoconcentration. Anaemia may be due to reduced red cell mass (decreased red cell production or survival) or haemodilution. The latter is common in critically ill patients. In severe anaemia there may be a hyperdynamic circulation which, if severe, may decompensate to cardiac failure. In this case, blood transfusion must be performed with extreme care to avoid fluid overload, or in association with plasmapheresis. Differential diagnosis of anaemia includes: